Luke A J O'Neill

Trinity College Dublin, Dublin, Leinster, Ireland

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Publications (260)2373 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Bordetella pertussis causes whooping cough, an infectious disease of the respiratory tract that is re-emerging despite high vaccine coverage. Here we examined the role of Toll-like receptor (TLR) adapter protein Mal in the control of B. pertussis infection in the lungs. We found that B. pertussis bacterial load in the lungs of Mal-defective (Mal(-/-)) mice exceeded that of wild-type (WT) mice by up to 100-fold and bacteria disseminated to the liver in Mal(-/-) mice and 50% of these mice died from the infection. Macrophages from Mal(-/-) mice were defective in an early burst of pro-inflammatory cytokine production and in their ability to kill or constrain intracellular growth of B. pertussis. Importantly, the B. pertussis bacterial load in the lungs inversely correlated with the number of alveolar macrophages. Despite the maintenance and expansion of other cell populations, alveolar macrophages were completely depleted from the lungs of infected Mal(-/-) mice, but not from infected WT mice. Our findings define for the first time a role for a microbial pattern-recognition pathway in the survival of alveolar macrophages and uncover a mechanism of macrophage-mediated immunity to B. pertussis in which Mal controls intracellular survival and dissemination of bacteria from the lungs.Mucosal Immunology advance online publication, 17 December 2014; doi:10.1038/mi.2014.125.
    Mucosal Immunology 12/2014; · 7.54 Impact Factor
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    Silvia Galván-Peña, Luke A J O'Neill
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    ABSTRACT: Studying the metabolism of immune cells in recent years has emphasized the tight link existing between the metabolic state and the phenotype of these cells. Macrophages in particular are a good example of this phenomenon. Whether the macrophage obtains its energy through glycolysis or through oxidative metabolism can give rise to different phenotypes. Classically activated or M1 macrophages are key players of the first line of defense against bacterial infections and are known to obtain energy through glycolysis. Alternatively activated or M2 macrophages on the other hand are involved in tissue repair and wound healing and use oxidative metabolism to fuel their longer-term functions. Metabolic intermediates, however, are not just a source of energy but can be directly implicated in a particular macrophage phenotype. In M1 macrophages, the Krebs cycle intermediate succinate regulates HIF1α, which is responsible for driving the sustained production of the pro-inflammatory cytokine IL1β. In M2 macrophages, the sedoheptulose kinase carbohydrate kinase-like protein is critical for regulating the pentose phosphate pathway. The potential to target these events and impact on disease is an exciting prospect.
    Frontiers in Immunology 09/2014; 5:420.
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    ABSTRACT: TLR4 interactor with leucine-rich repeats (TRIL) is a brain-enriched accessory protein that is important in TLR3 and TLR4 signaling. In this study, we generated Tril(-/-) mice and examined TLR responses in vitro and in vivo. We found a role for TRIL in both TLR4 and TLR3 signaling in mixed glial cells, consistent with the high level of expression of TRIL in these cells. We also found that TRIL is a modulator of the innate immune response to LPS challenge and Escherichia coli infection in vivo. Tril(-/-) mice produce lower levels of multiple proinflammatory cytokines and chemokines specifically within the brain after E. coli and LPS challenge. Collectively, these data uncover TRIL as a mediator of innate immune responses within the brain, where it enhances neuronal cytokine responses to infection.
    Journal of immunology (Baltimore, Md. : 1950). 07/2014;
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    ABSTRACT: Programmed Cell Death Protein 4 (PDCD4) is a tumor suppressor and has also been shown to suppress production of the immuno modulatory cytokine IL-10. The precise role of PDCD4 in IL-10 induction in macrophages is still not fully understood. Incubation of macrophages with inhibitors of PI3K and mTOR blocked LPS-stimulated PDCD4 degradation and expression of c-Maf and IL-10 production. PDCD4 and the transcription factor Twist2 were shown to form a complex in untreated cells. LPS disrupted the complex allowing Twist2 to bind to the c-Maf promoter. PI3K and mTOR inhibitors prevented this disruption by stabilizing PDCD4 and thereby decreased Twist2 binding to the c-Maf promoter and induction of c-Maf mRNA. These results indicate a regulatory role for PDCD4 and Twist2 in LPS-induced IL-10 production in macrophages. LPS promotes PDCD4 degradation via a pathway involving PI3K and mTOR, releasing Twist2, which induces IL-10 via c-Maf.
    The Journal of biological chemistry. 06/2014;
  • Annals of the Rheumatic Diseases 06/2014; 73(Suppl 2):698-698. · 9.11 Impact Factor
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    ABSTRACT: Bacterial lipopolysaccharide (LPS) stimulation of macrophages and inflammation via the Toll-like receptor 4 (TLR4) signalling pathway through NFκΒ generates reactive oxygen species (ROS) and pro-inflammatory cytokines such as IL-1β, IL-6 and TNFα. Since GSTO1-1 can catalyze redox reactions such as the deglutathionylation of proteins and has also been implicated in the release of IL-1β we investigated its role in the development of LPS mediated inflammation. Our data show that sh-RNA knock down of GSTO1-1 in macrophage-like J774.1A cells blocks the expression of NADPH oxidase 1 and the generation of ROS after LPS stimulation. Similar results were obtained with a GSTO1-1 inhibitor. In order to maintain high ROS levels during an inflammatory response, LPS stimulation causes the suppression of enzymes such as catalase and glutathione peroxidase that protect against oxidative stress. The knock down of GSTO1-1 also attenuates this response. Our data indicate that GSTO1-1 needs to be catalytically active and mediates its effects on the LPS/TLR4 inflammatory pathway upstream of NFκΒ. These data suggest that GSTO1-1 is a novel target for anti-inflammatory intervention.
    Free radical biology & medicine. 05/2014;
  • Luke A J O'Neill
    Nature Immunology 03/2014; 15(4):314-5. · 26.20 Impact Factor
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    ABSTRACT: Background: Toll-like receptors (TLRs) play a central role in the recognition and response to microbial pathogens, and in the maintenance and function of the epithelial barrier integrity in the gut. The protein MyD88 adaptor-like (Mal/TIRAP) serves as a bridge between TLR2/TLR4 and MyD88 mediated signalling to orchestrate downstream inflammatory responses. While MyD88 has an essential function in the maintenance of intestinal homeostasis, a role for Mal in this context is less well described. Methods: Colitis was induced in wild type (WT) and Mal-deficient (Mal(-/-)) mice by administration of dextran sodium sulfate (DSS). Colitis-associated cancer was induced by DSS and azoxymethane (AOM) treatment. Chimeric mice were generated by total-body gamma irradiation followed by transplantation of bone marrow cells. Results: In the DSS model of colon epithelial injury, Mal(-/-) mice developed increased inflammation and severity of colitis relative to WT mice. Mal(-/-) mice demonstrated the presence of inflammatory cell infiltrates, increased crypt proliferation, and presence of neo-formations. Furthermore, in the AOM/DSS model, Mal(-/-) mice had greater incidence of tumours. Mal(-/-) and WT bone marrow chimeras demonstrated that non-haematopoietic cell expression of Mal had an important protective role in the control of intestinal inflammation and inflammation-associated cancer. Conclusions: Mal is essential for the maintenance of intestinal homeostasis and expression of Mal in non-haematopoietic cells prevents chronic intestinal inflammation that may predispose to colon neoplasia.
    AJP Gastrointestinal and Liver Physiology 03/2014; · 3.65 Impact Factor
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    ABSTRACT: Immune parameters change with time of day and disruption of circadian rhythms has been linked to inflammatory pathologies. A circadian-clock-controlled immune system might allow an organism to anticipate daily changes in activity and feeding and the associated risk of infection or tissue damage to the host. Responses to bacteria have been shown to vary depending on time of infection, with mice being more at risk of sepsis when challenged ahead of their activity phase. Studies highlight the extent to which the molecular clock, most notably the core clock proteins BMAL1, CLOCK, and REV-ERBα, control fundamental aspects of the immune response. Examples include the BMAL1:CLOCK heterodimer regulating toll-like receptor 9 (TLR9) expression and repressing expression of the inflammatory monocyte chemokine ligand (CCL2) as well as REV-ERBα suppressing the induction of interleukin-6. Understanding the daily rhythm of the immune system could have implications for vaccinations and how we manage infectious and inflammatory diseases.
    Immunity 02/2014; 40(2):178-186. · 19.80 Impact Factor
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    ABSTRACT: The apoptosis associated speck-like protein containing a CARD (ASC) is an essential component of several inflammasomes, multiprotein complexes that regulate caspase-1 activation and inflammation. We report here an interaction between promyelocytic leukemia protein (PML) and ASC. We observed enhanced formation of ASC dimers in PML- deficient macrophages. These macrophages also display enhanced levels of ASC in the cytosol. Furthermore, IL-1β production was markedly enhanced in these macrophages in response to both NLRP3 and AIM2 inflammasome activation and following BMDM infection with herpes simplex virus-1 (HSV-1) and Salmonella typhimurium. Collectively our data indicate that PML limits ASC function, retaining ASC in the nucleus.
    Journal of Biological Chemistry 01/2014; · 4.65 Impact Factor
  • Susan R Quinn, Luke A O'Neill
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    ABSTRACT: Recent studies have shown an important interplay between Interleukin 10 (IL-10) and microRNAs. IL-10 can be directly post-transcriptionally regulated by several microRNA, including miR-106a, miR-4661, miR-98, miR-27, let7 and miR-1423p/5p. miRNA targeting of IL-10 has been suggested to play a role in autoimmune and inflammatory diseases such as SLE, reperfusion injury and asthma. Another miRNA, miR-21, has been shown to indirectly regulate IL-10 via downregulation of the IL-10 inhibitor PDCD4. The targeting of IL-10 in this way has been linked to host defence modulation by Mycobacterium leprae. Viral miRNAs, such as miR-K12-3 from Kaposi's sarcoma-associated herpesvirus (KSHV), can also decrease IL-10 to promote tumour development. Finally this interplay can operate in a feedback loop, with IL-10 capable of regulating microRNAs, upregulating those that can contribute to exerting the anti-inflammatory response, such as miR-187, and downregulating those that are highly pro-inflammatory, such as miR-155. Understanding the two-way regulation between miRNA and IL-10 is giving rise to new insights into this important cytokine.
    Current topics in microbiology and immunology 01/2014; 380:145-55. · 4.86 Impact Factor
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    ABSTRACT: The prognosis of epithelial ovarian cancer is poor in part due to the high frequency of chemoresistance. Recent evidence points to the Toll-like receptor-4 (TLR4), and particularly its adaptor protein MyD88, as one potential mediator of this resistance. This study aims to provide further evidence that MyD88 positive cancer cells are clinically significant, stem-like and reproducibly detectable for the purposes of prognostic stratification. Expression of TLR4 and MyD88 was assessed immunohistochemically in 198 paraffin-embedded ovarian tissues and in an embryonal carcinoma model of cancer stemness. In parallel, expression of TLR4 and MyD88 mRNA and regulatory microRNAs (miR-21 and miR-146a) was assessed, as well as in a series of chemosensitive and resistant cancer cells lines. Functional analysis of the pathway was assessed in chemoresistant SKOV-3 ovarian cancer cells. TLR4 and MyD88 expression can be reproducibly assessed via immunohistochemistry using a semi-quantitative scoring system. TLR4 expression was present in all ovarian epithelium (normal and neoplastic), whereas MyD88 was restricted to neoplastic cells, independent of tumour grade and associated with reduced progression-free and overall survival, in an immunohistological specific subset of serous carcinomas, p<0.05. MiR-21 and miR-146a expression was significantly increased in MyD88 negative cancers (p<0.05), indicating their participation in regulation. Significant alterations in MyD88 mRNA expression were observed between chemosensitive and chemoresistant cells and tissue. Knockdown of TLR4 in SKOV-3 ovarian cells recovered chemosensitivity. Knockdown of MyD88 alone did not. MyD88 expression was down-regulated in differentiated embryonal carcinoma (NTera2) cells, supporting the MyD88+ cancer stem cell hypothesis. Our findings demonstrate that expression of MyD88 is associated with significantly reduced patient survival and altered microRNA levels and suggest an intact/functioning TLR4/MyD88 pathway is required for acquisition of the chemoresistant phenotype. Ex vivo manipulation of ovarian cancer stem cell (CSC) differentiation can decrease MyD88 expression, providing a potentially valuable CSC model for ovarian cancer.
    PLoS ONE 01/2014; 9(6):e100816. · 3.53 Impact Factor
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    ABSTRACT: MicroRNA-155 (miR-155) is highly expressed in many cancers such as B cell lymphomas and myeloid leukaemia, and inflammatory disorders such as rheumatoid arthritis, atopic dermatitis and multiple sclerosis. The role of miR-155 as both a promoter of inflammation and an oncogenic agent provides a clear need for miR-155 itself to be stringently regulated. We therefore investigated the transcriptional regulation of miR-155 in response to the respective pro- and anti-inflammatory mediators LPS and IL-10. Bioinformatic analysis revealed Ets binding sites on the miR-155 promoter, and we found that Ets2 is critical for miR-155 induction by LPS. Truncation and mutational analysis of the miR-155 promoter confirmed the role of the Ets2 binding site proximal to the transcription start site for LPS responsiveness. We observed increased binding of Ets2 to the miR-155 promoter and Ets2 deficient mice displayed decreased induction of miR-155 in response to LPS. IL-10 inhibited the induction of Ets2 mRNA and protein by LPS, thereby decreasing Ets2 function on the pri-155 promoter. We have thus identified Ets2 as a key novel regulator in both the positive and negative control of miR-155 in the inflammatory response.
    Journal of Biological Chemistry 12/2013; · 4.65 Impact Factor
  • Evanna Mills, Luke A J O'Neill
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    ABSTRACT: Succinate is an intermediate of the tricarboxylic acid (TCA) cycle, and plays a crucial role in adenosine triphosphate (ATP) generation in mitochondria. Recently, new roles for succinate outside metabolism have emerged. Succinate stabilizes the transcription factor hypoxia-inducible factor-1α (HIF-1α) in specific tumors and in activated macrophages, and stimulates dendritic cells via its receptor succinate receptor 1. Furthermore, succinate has been shown to post-translationally modify proteins. This expanding repertoire of functions for succinate suggests a broader role in cellular activation. We review the new roles of succinate and draw parallels to other metabolites such as NAD(+) and citrate whose roles have expanded beyond metabolism and into signaling.
    Trends in cell biology 12/2013; · 12.12 Impact Factor
  • Luke A J O'Neill
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    ABSTRACT: The Nlrp3 inflammasome is a key controller of the proinflammatory cytokine IL-1β. Iyer and colleagues (2013) demonstrate that Nlrp3 activators promote an interaction between cardiolipin in mitochondria and Nlrp3. Cardiolipin is thus a hydrophobic danger signal that, upon translocation to the outer mitochondrial membrane, activates Nlrp3, promoting inflammation.
    Cell metabolism 11/2013; 18(5):610-2. · 17.35 Impact Factor
  • Eva M Palsson-McDermott, Luke A J O'Neill
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    ABSTRACT: Inflammatory immune cells, when activated, display much the same metabolic profile as a glycolytic tumor cell. This involves a shift in metabolism away from oxidative phosphorylation towards aerobic glycolysis, a phenomenon known as the Warburg effect. The result of this change in macrophages is to rapidly provide ATP and metabolic intermediates for the biosynthesis of immune and inflammatory proteins. In addition, a rise in certain tricarboxylic acid cycle intermediates occurs notably in citrate for lipid biosynthesis, and succinate, which activates the transcription factor Hypoxia-inducible factor. In this review we take a look at the emerging evidence for a role for the Warburg effect in the immune and inflammatory responses. The reprogramming of metabolic pathways in macrophages, dendritic cells, and T cells could have relevance in the pathogenesis of inflammatory and metabolic diseases and might provide novel therapeutic strategies.
    BioEssays 09/2013; · 5.42 Impact Factor
  • Nicholas J Bernard, Luke A O'Neill
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    ABSTRACT: The family of type 1 transmembrane proteins known as Toll-like receptors (TLRs) provide early immune system recognition and response to infection. In order to transmit their signal to the nucleus and initiate activation of pro-inflammatory and anti-microbial genes, TLRs must initiate a cytoplasmic signalling cascade, which is alternately controlled by 6 known signalling adaptors. These signaling adaptors are crucial for activating the correct immune response to any given TLR / pathogen interaction. This review will focus on one of those adaptors, MyD88 adaptor-like (Mal), also known as TIRAP. Mal is critical for signalling by the best studied of the TLRs, the Gram negative bacterial lipopolysaccharide (LPS) sensor, TLR4. Mal's role in TLR2 signalling in response to activation of the bacterial lipopeptide receptor, TLR2, is more contentious. Mal is a component of the so-called 'MyD88-dependent pathway' in TLR4 signalling. Recent advances in our understanding of the signalling pathways downstream of Mal highlight MyD88-indpendent roles, thus positioning Mal as multifunctional and integral for the molecular control of bacterial infections as well as inflammatory diseases. Here we describe the sequence of molecular events involved in the signalling pathways controlled by Mal, and the importance of Mal in driving host protection against a variety of bacteria, with specific attention to the evidence for Mal's role in TLR2 signalling, recent structural findings that have altered our understanding of Mal signalling, and evidence that single nucleotide polymorphisms (SNPs) of Mal are responsible for variations in population level resistance and susceptibility to bacterial infection. © 2013 IUBMB Life, 65(9):777-786, 2013.
    International Union of Biochemistry and Molecular Biology Life 09/2013; 65(9):777-86. · 2.79 Impact Factor
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    ABSTRACT: An inducible program of inflammatory gene expression is central to antimicrobial defenses. Signal-dependent activation of transcription factors, transcriptional co-regulators, and chromatin modifying factors collaborate to control this response. Here, we identify a long noncoding RNA that acts as a key regulator of this inflammatory response. Pattern recognition receptors such as the Toll-like receptors induce the expression of numerous lncRNAs. One of these, lincRNA-Cox2 mediates both the activation and repression of distinct classes of immune genes. Transcriptional repression of target genes is dependent on interactions of lincRNA-Cox2 with heterogeneous nuclear ribonucleoprotein A/B and A2/B1. Collectively, these studies unveil a central role of lincRNA-Cox2 as a broad acting regulatory component of the circuit that controls the inflammatory response.
    Science 08/2013; · 31.20 Impact Factor
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    ABSTRACT: In this study we describe a previously unreported function for NFκB2, an NFκB family transcription factor, in antiviral immunity. NFκB2 is induced in response to Poly(I:C), a mimic of viral dsRNA. Poly(I:C), acting via TLR3, induces p52-dependent transactivation of a reporter gene in a manner that requires the kinase activity of IKKε and the transactivating potential of RelA/p65. We identify a novel NFκB2 binding site in the promoter of the transcription factor Sp1 which is required for Sp1 gene transcription activated by Poly(I:C). We show that Sp1 is required for IL-15 induction by both Poly(I:C) and Respiratory Syncitial Virus, a response that also requires NFκB2 and IKKε. Our study identifies NFκB2 as a target for IKKε in anti-viral immunity and describes, for the first time, a role for NFκB2 in the regulation of gene expression in response to viral infection.
    Journal of Biological Chemistry 07/2013; · 4.65 Impact Factor
  • Anne F McGettrick, Luke A J O'Neill
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    ABSTRACT: The interplay between immunity, inflammation and metabolic changes is a growing field of research. Toll-like receptors (TLRs) and NOD-like receptors (NLRs) are families of innate immune receptors and their role in our immune response is well documented. Exciting new evidence is emerging with regard to their role in the regulation of metabolism and the activation of inflammatory pathways during the progression of metabolic disorders such as type 2 diabetes and atherosclerosis. The pro-inflammatory cytokine IL-1β appears to play a central role in these disorders. There is also evidence for metabolites such as NAD+ (acting via deacetylases such as SIRT1 and SIRT2) and succinate (which regulates the transcription factor HIF1α) being signals which regulate innate immunity. In addition the over-production of metabolites extracellularly such as uric acid and cholesterol crystals act as signals sensed by NLRP3, leading to the production of IL-1β. These observations are casting new light on the role of metabolism during host defense and inflammation.
    Journal of Biological Chemistry 06/2013; · 4.65 Impact Factor

Publication Stats

16k Citations
2,373.00 Total Impact Points

Institutions

  • 1992–2014
    • Trinity College Dublin
      • • Biochemistry
      • • School of Biochemistry and Immunology
      Dublin, Leinster, Ireland
  • 1994–2013
    • Trinity College
      • Biochemistry
      Hartford, Connecticut, United States
  • 2012
    • University of North Carolina at Chapel Hill
      North Carolina, United States
    • Coombe Women & Infants University Hospital
      Dublin, Leinster, Ireland
    • Radboud University Nijmegen
      • Department of General Internal Medicine
      Nijmegen, Provincie Gelderland, Netherlands
  • 2003–2012
    • University of Bath
      • Department of Pharmacy and Pharmacology
      Bath, ENG, United Kingdom
  • 2011
    • St. James's Hospital
      Dublin, Leinster, Ireland
    • University of Cambridge
      • Department of Biochemistry
      Cambridge, ENG, United Kingdom
  • 2005
    • University of Glasgow
      • Institute of Infection, Immunity and Inflammation
      Glasgow, SCT, United Kingdom
  • 1995
    • Dublin City University
      • School of Biotechnology
      Dublin, Leinster, Ireland